000 AXNT20 KNHC 201800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED OCT 20 2010 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE WITH ACCOMPANYING SHOWERS AND THUNDERSTORMS ARE OVER THE W CARIBBEAN SEA ABOUT 60 MILES SOUTHWEST OF GRAND CAYMAN. AT 20/1800 UTC A PARTIALLY EXPOSED 1007 MB LOW IS CENTERED NEAR 17N82W. SCATTERED HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE ENE OF THE LOW CENTER FROM 16N-22N BETWEEN 76W-82W INCLUDING THE WESTERN TIP OF JAMAICA. ALTHOUGH ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE FOR DEVELOPMENT...CONDITIONS ARE EXPECTED TO BECOME SOMEWHAT MORE FAVORABLE FOR A TROPICAL DEPRESSION TO FORM DURING THE NEXT DAY OR SO. THERE IS A HIGH CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT DRIFTS TO THE SOUTH OR SOUTHEAST. INTERESTS IN THE NORTHWESTERN CARIBBEAN SEA SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS DISTURBANCE. REGARDLESS OF DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER THE CAYMAN ISLANDS AND JAMAICA DURING THE NEXT COUPLE OF DAYS. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 7N18W 6N27W 10N36W...RESUMING NEAR 8N42W 6N52W 10N62W. A SURFACE TROUGH IS N OF THE ITCZ EXTENDING FROM 18N35W THROUGH A 1012 MB LOW NEAR 13N39W TO 10N40W WITH CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 110 NM ON EITHER SIDE OF THE THROUGH AXIS. CLUSTERS OF SCATTERED WEAK TO MODERATE CONVECTION ARE FROM 3N-15N E OF 23W INCLUDING THE W COAST OF AFRICA AND THE PRIME MERIDIAN. CLUSTERS OF SCATTERED WEAK CONVECTION ARE WITHIN 60 NM ON EITHER SIDE OF THE ITCZ AXIS BETWEEN 23W AND 31W. SIMILAR CONVECTION IS W OF 56W. ...DISCUSSION... GULF OF MEXICO... A BROAD MID-UPPER RIDGE CENTERED INLAND OVER CENTRAL MEXICO IS DOMINATING MOST OF THE AREA OF DISCUSSION GIVING MOSTLY CLEAR SKIES AND WITH FEW AREAS OF SCATTER LOW LEVEL STRATOCUMULUS CLOUDS EMBEDDED IN THE LIGHT ANTICYCLONIC SFC FLOW. A WEAK SURFACE RIDGE REMAINS OVER THE NW GULF ANCHORED BY A 1018 MB HIGH NEAR 27N93W. THE ONLY AREA OF ACTIVE WEATHER IS OCCURRING OVER THE FAR SW COASTAL WATERS OF THE FLORIDA PENINSULA AND THE FLORIDA STRAITS...E OF 83W S OF 26N...DUE TO DIFFLUENCE ALOFT COUPLED WITH LOW LEVEL MOISTURE IN THE FAR SE BASIN. STRONG SUBSIDENCE AND DRY AIR ALOFT COVERS THE REMAINDER OF THE AREA. CARIBBEAN SEA... A LOW PRESSURE SYSTEM IS OVER THE WESTERN CARIBBEAN NEAR 17N82W. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. ELSEWHERE OUTSIDE THE CONVECTION ASSOCIATED TO THE SPECIAL FEATURE...DRY AND STABLE AIR ALOFT COVERS MOST OF THE AREA OF DISCUSSION PROVIDING RELATIVELY FAIR WEATHER CONDITIONS WITH A FEW AREAS OF SCATTERED SHOWERS EMBEDDED IN THE TRADE WINDS. WITHIN THIS BROAD REGION OF DRYNESS...AN ELONGATED N/S UPPER LOW REMAINS OVER THE FAR EAST BASIN STILL NOT PRODUCING ANY SIGNIFICANT WEATHER. ATLANTIC OCEAN... A BROAD MID-UPPER LEVEL TROUGH COVERS THE THE EASTERN CONUS. A BROAD UPPER RIDGE ANCHORED IS IN THE CENTRAL ATLC BY A 1024 MB HIGH NEAR 33N53W. THIS WEATHER SCENARIO IS GENERATING AN AREA OF SURFACE CONVERGENCE FROM 23N-30N BETWEEN 66W-71W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS OBSERVED IN THIS AREA. A WEAK UPPER LEVEL TROUGH OVER THE EASTERN ATLC SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N23W...EXTENDING SW TO 29N28W. FROM THAT POINT...A SURFACE TROUGH CONTINUES TO NEAR 26N39W...BECOMING A SHEAR/REMNANT CLOUD LINE TO NEAR 22N49W. SCATTERED WEAK CONVECTION IS WITHIN 80 NM EAST OF THE COLD FRONT. SCATTERED WEAK CONVECTION IS WITHIN 40 NM ON EITHER SIDE OF THE SURFACE TROUGH. POSSIBLE ISOLATED CONVECTION IS WITHIN 30 NM ON EITHER SIDE OF THE SHEAR LINE. THE REST OF THE AREA OF DISCUSSION REMAINS UNDER FAIR WEATHER CONDITIONS SUPPORTED BY A DRY UPPER ATMOSPHERE SEEN ON WATER VAPOR IMAGERY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA